Police are still awaiting the forensic results from ESR following the sudden death of Raetihi boy Antony Herewini-Christiansen on December 7.
Rural Ruapehu Detective Senior Sergeant Keith Borrell of Taranaki police said a staff of six was working in Raetihi on the investigation.
Mr Borrell said once the results were received, they would be able to determine how the 9-year old died.
Antony lived in a house in Duncan St, Raetihi, with his mother, younger brother and two older sisters.
Police investigating his death began treating it as suspicious after traces of a prescription medicine were found in his system during initial tests.